Webstart temp folder permissions problem a bug?

Webstart uses a temp folder to store the downloaded files.
This folder is often not writable for our customers/users of our program.
(e.g. A sysadmin installs java as administrator and the user can't write in the temp folder of the administrator off course)
This results in "failed to load application"

Can I consider this a bug in Javaws?

it should prompt the user to select a folder if javaws cannot write to its cache/temp folder.
to simply fail is not a good way to give confidence in our program.